Fast shutdown of large scale-up processes

ABSTRACT

A system for shutting down a process of a database is provided. In some aspects, the system performs operations including tracking, during startup of a process, code locations of a process in the at least one memory. The operations may further include tracking, during runtime of the process and in response to the tracking the code locations, memory segments of the at least one memory allocated to the process. The operations may further include receiving an indication for a shutdown of a process. The operations may further include waking, in response to the indication, at least one processing thread of a plurality of processing threads allocated to a database system. The operations may further include allocating a list of memory mappings to the plurality of processing threads. The operations may further include freeing, by the first processing thread, the physical memory assigned to the processing thread by the memory mappings.

TECHNICAL FIELD

The subject matter described herein relates generally to databaseprocessing and, more specifically, to fast shutdown of large scale-upprocesses in database systems.

BACKGROUND

A database may be configured to store a plurality of electronic datarecords. The database may be coupled with a database management system(DBMS) that supports a variety of database operations for accessing thedata records held in the database including, for example, structuredquery language (SQL) queries and/or the like. The database may be storedin a cloud server.

SUMMARY

Systems, methods, and articles of manufacture, including computerprogram products, are provided for data management. In one aspect, thereis provided a system. The system may include at least one data processorand at least one memory. The at least one memory may store instructionsthat result in operations when executed by the at least one dataprocessor. The operations may include tracking, during a startup of aprocess, code locations of the process in the at least one memory. Theoperations may further include tracking, during runtime of the processand in response to the tracking the code locations, memory segments ofthe at least one memory allocated to the process. The operations mayfurther include receiving an indication for a shutdown of a process. Theoperations may further include waking, in response to the indication, atleast one processing thread of a plurality of processing threadsallocated to a database system. The operations may further includeallocating a list of memory mappings to the plurality of processingthreads, the list of memory mappings comprising a subset of the memorysegments allocated to the process, the subset assigned to a firstprocessing thread of the plurality of processing threads. The operationsmay further include freeing, by the first processing thread, thephysical memory assigned to the processing thread by the memorymappings. The operations may further include returning, after allprocessing threads finish freeing the physical memory assigned to theprocessing threads, control for shutting down the process to anoperating system of the at least one data processor.

In some variations, one or more features disclosed herein including thefollowing features may optionally be included in any feasiblecombination. For example, the tracking the code locations may includecalling an operation to identify memory segments related to the codelocations associated with the process. The freeing may be performedconcurrently by each thread of the plurality of processing threads. Thesubset of memory may be based on a memory size. The allocating mayinclude allocating particular memory segments to each thread of theplurality of processing threads. The freeing the physical memory mayinclude freeing memory pages from a page table. The allocating may bebased on the tracked memory segments. The allocating may be based on amachine learning model. The operations may further include updating themachine learning model based on a historic allocation of memory mappingsto the plurality of processing threads. The allocating may be based onthe updated machine learning model.

Implementations of the current subject matter may include, but are notlimited to, methods consistent with the descriptions provided herein aswell as articles that include a tangibly embodied machine-readablemedium operable to cause one or more machines (e.g., computers, etc.) toresult in operations implementing one or more of the described features.Similarly, computer systems are also described that may include one ormore processors and one or more memories coupled to the one or moreprocessors. A memory, which may include a non-transitorycomputer-readable or machine-readable storage medium, may include,encode, store, or the like one or more programs that cause one or moreprocessors to perform one or more of the operations described herein.Computer implemented methods consistent with one or more implementationsof the current subject matter may be implemented by one or more dataprocessors residing in a single computing system or multiple computingsystems. Such multiple computing systems may be connected and mayexchange data and/or commands or other instructions or the like via oneor more connections, including, for example, to a connection over anetwork (e.g. the Internet, a wireless wide area network, a local areanetwork, a wide area network, a wired network, or the like), via adirect connection between one or more of the multiple computing systems,etc.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims. While certain features of the currently disclosed subject matterare described for illustrative purposes in relation to web applicationuser interfaces, it should be readily understood that such features arenot intended to be limiting. The claims that follow this disclosure areintended to define the scope of the protected subject matter.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associated with the disclosed implementations. In thedrawings,

FIG. 1 depicts a functional block diagram of a system in which featuresconsistent with the described subject matter may be implemented;

FIG. 2 depicts an example of a graph illustrating time consumptionversus a memory size, in accordance with some example implementations;

FIG. 3 depicts a flowchart illustrating a process for shutting down aprocess in a database management system, in accordance with some exampleimplementations; and

FIG. 4 depicts a block diagram illustrating a computing apparatus, inaccordance with some example implementations.

When practical, similar reference numbers denote similar structures,features, or elements.

DETAILED DESCRIPTION

Large scale-up systems like databases tend to acquire a lot of resourcesand might cache them for future usage. In exceptional cases for examplewhen unrecoverable errors occur, the process may need to be shut downimmediately. The operating system may clean up all remaining resourcesas fast as possible to be able to reallocate them to other processes.

In some databases including in-memory databases and/or in-memorycolumn-oriented relational database systems (e.g., SAP HANA) may involvea large quantity of computational and/or memory resources. A databaseshutdown process may consume a significant amount of time. For example,on a system having up to 48 TB of memory, the shutdown process may takeup to approximately 68 minutes. This may increase the process downtimesignificantly. Next generation operating systems may increase thephysical limit from 48 TB up to 4PB of memory. This would imply that thedatabase shutdown process may take up to 6144 minutes (e.g., over 4days). The increased time consumption is due to the operating systemfreeing the resources using one thread only.

Implementations described herein relate to a process of shifting most ofthe processing work done during a process shutdown (e.g., a databaseprocess shutdown) to be accomplished with concurrent parallel processingthreads before an operating system takes over the process shutdown. Theshutdown processing work may be accomplished by a database process inparallel with multiple processing (e.g., CPU) threads rather than by theoperating system using a single thread only. This parallel, concurrentprocessing across multiple processing threads may speed up the shutdownprocess significantly. Decisions on whether to shut down a process maybe triggered by electronic signals, which may be transmitted and/orhandled by the process itself before returning execution to theoperating system. Concurrent clearing of physical memory describedherein may reduce the time for process shutdown to more quickly free upmemory for other processes and/or tasks.

FIG. 1 illustrates a functional block diagram of a system 100 in whichfeatures consistent with the described subject matter may beimplemented. As illustrated, the system 100 may include a computingsystem 110 capable of communicating with one or more user access devices140. The computing system 110 may utilize one or more interfaces 118 forcommunication. Communication among the devices of the system 100 may bethrough the use of direct communications, such as through the use of awireless connection like Bluetooth, near-field communication (NFC),ZigBee, and/or the like, and/or a wired connection such as universalserial bus (USB) and/or the like. Communication may additionally oralternatively occur through indirect communications, such as over anetwork 160 (e.g., a local area network, a wide area network, a wirelessnetwork, the Internet, or the like).

Communication over the network 160 may utilize a network access device165, such as a base station, a Node B, an evolved Node B (eNB), anaccess nodes (ANs), a hotspot, and/or the like. Any of the user accessdevice 140 may include personal computers, desktop computers, laptops,workstations, cell phones, digital media devices, smart phones, smartwatches, PDAs (personal digital assistants), tablets, hardware/softwareservers, sensors, sensor devices, terminals, access terminals (ATs),mobile stations, user equipment (UE), subscriber units, and/or the like.

As illustrated, the computing system 110 may include core software 112and/or one or more software modules 114. The core software 112 mayprovide one or more features of a high-level programming softwaresystem. The software modules 114 may provide more specializedfunctionality. For example, the core software 112 and/or softwaremodules 114 may include database management features, such as thosedescribed herein.

The core software 112 or other similar software/hardware may be capableof accessing a database layer, such as the database 120, which includesa page table 122 and virtual memory area (VMA) tree 121 to monitormemory (e.g., memory 116, a memory of the database 120, or the like).The VMA tree 121 may store metadata describing memory areas (e.g., astart address of memory, an end address of memory, a type of memory(stack, heap, library, etc.)) The page table 122 may store a mappingbetween virtual memory addresses and physical memory addresses and maypoint to physical memory pages that may store any type of data,including transactional data, metadata, timestamp data, lock data,access data, master data, company/business data, and/or the like. Thecomputing system 110 may include a cloud server (not shown) storingtable partitions.

One or more of the software modules 114 may be configured to utilizedata stored in the memory 116, data stored in the database 120, and/ordata otherwise accessible to the computing system 110. As furtherillustrated, the computing system 110 may be capable of utilizingexternal software 130. The external software 130 may provide additionalfunctionalities or services, which may not be available at the computingsystem 110. The external software 130 may include cloud services. Thecomputing system 110 may aggregate or otherwise provide a gateway viawhich users may access functionality provided the external software 130.The database 120 and/or the external software 130 may be located acrossone or more servers, and/or communication among the computing system110, the database, and/or the external software 130 may occur over thenetwork 160.

At least a portion of the illustrated system 100 may include hardwareand/or software that interacts with a database, users, and/or othersoftware applications for defining, creating, and/or updating data, forreceiving, handling, optimizing, and/or executing database queries,and/or for running software/applications (e.g., software modules 114,and/or external software 130) which utilize a database. The database 120may be a structured, organized collection of data, such as schemas,tables, queries, reports, views, and/or the like, which may be processedfor information. The database 120 may be physically stored in a hardwareserver or across a plurality of hardware servers. The database 120 mayinclude a row store database, a column-store database, a schema-lessdatabase, or any other type of database. The computing system 110 may beconfigured to perform OLTP (online transaction processing) and/or OLAP(online analytical processing), which may include complex analytics andtasks. Any of the data stored in the database 120 may additionally oralternatively be stored in the memory 116, which may be required inorder to process the data. As noted, a large accumulation of table datastored in the database 120 may affect the performance and/or resourcesof the memory 116, the core software 112, and/or a processor of thecomputing system 110.

The core software 112 may be configured to load the information from thedatabase 120 to memory 116 (e.g., main memory) in response to some eventand/or determination. For example, data may be retrieved from thedatabase 120 and/or loaded into the memory 116 based on receipt of aquery instantiated by a user or computer system, which may occur throughone or more user access device 140, external software 130, and/or thelike. At least a portion of the data for the database 120 may residein-memory (e.g., in random-access memory (RAM)), within the memory 116,for example. Data stored in-memory may be accessed faster than datastored in long term storage (also referred to herein as “on disk”).

Although the database 120 may be illustrated as described as beingseparate from the computing system 110, in various implementations, atleast a portion of the database 120 may be located within the memory 116of the computing system 110.

The computing system 110 may implement procedures for cleaning andclearing memory for a process shutdown. After freeing physical memory(e.g., removing physical memory pages from the page table 122), thecomputing system 110 may receive feedback regarding whether the cleaningand clearing of memory was correct and/or resulted in an improvedperformance. Additionally, after freeing physical memory for the processshutdown, an operating system of the computing system may complete thecleanup process and re-allocate memory resources to other processes.

In order to avoid a memory shortage due to the shutdown process beingunable to free memory resources quickly the computing system 110, mayperform periodic checks to determine whether the database may beoptimized by cleaning and clearing memory prior to shutdown of aprocess. For example, the computing system 110 may implement a log orprotocol to determine a current memory size of the database, how oftenthe memory of the database are accessed, and determine how they areused. The determining which memory resources to unload or clean up maybe based on one or more parameters to indicate a location of memoryresources and/or indicate that a loaded memory structure has not beenaccessed for a threshold time period and/or is not likely to be accessedwithin a threshold time period. The parameters may include the type ofdata, the size of data, a rate or quantity of out of memory (OOM)errors, a last time when the data was accessed, a type of access to thedata (e.g., read, write, etc.), and/or the like.

The computing system 110 may, during a startup of a process, track codelocations of the process (e.g., libraries) in memory. For example, thecomputing system 110 may retrieve a list of memory segments related tocode of the process. The computing system 110 may also distinguishbetween different types of access. Moreover, general housekeepingprocesses may not trigger loading unloaded tables, so costly reloads dueto housekeeping processes may be avoided.

The computing system 110 may distinguish between different types of datastructures. For example, the computing system 110 may distinguishbetween accessing and/or cleaning up the VMA tree 121 and/or the pagetable 122. For example, the computing system 110 may attempt to reduce(e.g., cleanup) the memory stored in the page table 122 and return thecleared memory resources to the operating system of the computing system110.

As noted above, distinguishing between the types of access may enablethe computing system 110 to more quickly free up physical memory for theprocess shutdown (e.g., memory from the page table 122) and re-assignthe freed memory resources to other processes (e.g., VMA table 121).

FIG. 2 depicts an example graph 200 illustrating time consumption versusa memory size, in accordance with some example implementations. In theexample of FIG. 2 , the processing time for shutting down a processincreases linearly with an increase in memory. This increase shownassumes the shutdown process is being executed by an operating systemusing a single processing thread. The larger time consumption shown atthe right hand side of FIG. 2 may detrimentally affect systemperformance because system resources may be tied up in the shutdownprocess for an extended period of time and unable to be deployedelsewhere.

In order to combat the increase in time consumption, it may bebeneficial to allocate the shutdown processing among multiple processingthreads. For example, a database management system may be allocatedmemory (e.g., memory 116) and processing resources (e.g., core software112) by an operating system of a computing system (e.g., computingsystem 110). The database management system (e.g., SAP HANA) may includecentral processing unit (CPU) threads for executing database processes.In some aspects, the CPU threads may be allocated by an operating systemof the computing system 110. The threads may allow application logicand/or processes to be separated into several concurrent executionpaths. This feature may be useful when complex applications and/orprocesses have many tasks that can be performed at the same time, asexplained further below for the shutdown process.

FIG. 3 depicts a flowchart illustrating a process 300 for shutting downa process, in accordance with some example implementations. Referring toFIGS. 1 and 4 , the process 300 may be performed by a computingapparatus such as, for example, the computing system 110, the useraccess device 140 and/or the access device 165, and/or the computingapparatus 400.

At operational block 310, the apparatus 400, for example, may, during astartup of a process, track the code locations of a process in memory.For example, the apparatus 400 may call an operation (e.g., Linuxoperation PROC/SELF/MAPS) to identify memory segments related to alocation of code associated with the process such as the process of thedatabase management system being terminated). It may be beneficial toidentify code (e.g., code libraries, stack, heap, or the like), so thatthe code is not deleted during the shutdown, termination process.

At operational block 320, the apparatus 400, for example, may, duringruntime of the process, track the memory segments allocated to theprocess. For example, in response to tracking the code locations inmemory, the apparatus 400 may call an operation (e.g., the Linuxoperation PROC/SELF/MAPS) to identify memory segments attached orassociated with the process. Tracking the memory segments allocated tothe process may include identifying and/or monitoring a start addressand an end address for the memory segments.

At operational block 330, the apparatus 400, for example, may, inresponse to receiving an indication of a shutting down the process, wakeup processing threads associated with the process. For example, aquantity of threads may be allocated to the database management systemfor running one or more database processes. In order to fully utilizethe allocated threads, the apparatus 400 may wake up any inactivethreads so that they may be applied to the concurrent, parallelprocessing of the shutdown process. Waking up a thread may refer tomaking an inactive thread active. The shutdown of the process may beindicated using electronic signals, which may be handled by the processitself (e.g., the database management system process) before returningexecution of the shutdown to the operating system. The electronicsignals may be either sent from outside the process (e.g., a crashsignal sent by the operating system) to terminate the process forcefullyor sent from the process itself as a consequence of an attempt to accessa memory address which does not refer to valid memory (e.g., physicalmemory may not be mapped at all at this address, memory may have wrongaccess rights such as only read rights but there is a write access orthe memory address may not be well aligned but the assembler instructionrequires appropriate alignment). In some aspects, only a subset of theallocated threads may be active and the remaining threads may beinactive.

At operational block 340, the apparatus 400, for example, may, duringtermination of the process, assign memory segments to a thread. Duringtermination of the process, the threads of the process may workconcurrently on returning memory to the OS. As described herein,termination of the process may be a regular shutdown (maintenancedowntime, upgrade) or a crash (e.g., crash signal) or some otherforceful termination.

During termination of the process, each thread of the process may beassigned which memory segments to return to the operating system. Forexample, a database management system (e.g., SAP HANA) may include 32CPU threads for processing database processes and/or applications. Theapparatus 400 may, in response to tracking the memory segments allocatedto the process, split the assigned memory segments into different groupsand apportion the groups to different threads. For example, theapparatus 400 may determine that memory segments 0-119 are allocated tothe process. The apparatus 400 may then allocate 16 threads to memorysegments 0-59, 8 threads to memory segments 60-89, and 8 threads tomemory segments 90-119. Each thread may receive a memory mappingindicating which memory segment(s) a thread is responsible for clearingduring the termination of the process. While specific assignments ofmemory segments to threads are described above, other assignments arepossible.

In some aspects, rather than being assigned to specific memory segments,each group of threads may be allocated a particular memory size to freeor clean up. In some aspects, assignments of memory to threads may use around robin strategy. For example, the first 1 GB may be returned bythread 1, then a second 1 GB by thread 2, . . . , nth GB by thread n, orthe like.

As noted with respect to block 330, if any of the 32 CPU threads wereinactive prior to receiving the indication of the shutdown of theprocess, then those inactive threads may be woken up so that they areactive to handle the processing indicated in the received memoryassignments to the processing threads. While specific quantities ofthreads and memory segments are described herein, other quantities arepossible.

At operational block 350, the apparatus 400, for example, may free thephysical memory assigned to each thread by the memory mapping. Forexample, in response to receiving the memory mappings, each thread maycommunicate to the operating system to free the physical memory assignedto the thread via the memory mapping. For example the thread may call anoperation (e.g., a madvise operation with an option madv_dontneedoperation or madv_free operation on Linux) to free memory resources(e.g., memory pages of the page table 122) associated with the thread(e.g., via the assigned memory mapping). The madvise operation refers toa system call to give advice or directions to the kernel about theaddress range beginning at a certain address.

At operational block 360, the apparatus 400, for example, may, inresponse to completion of the freeing, return control to the operatingsystem to finish termination of the process. For example, the freeing ofmemory resources by each thread may occur concurrently across themultiple threads (e.g., 32 threads). After all threads have finishedfreeing the assigned memory resources, execution of the terminationprocess may be returned to the operating system (e.g., operating systemof the computing system 110).

At operational block 370, the apparatus 400, for example, may, inresponse to the returning, may complete the termination of the processby the operating system. For example, the operating system of thecomputing system 110 may clean up all remaining memory resources as fastas possible to be able to re-assign them to other processes. As notedabove, the operating system clean-up may be completed by a singleprocessing thread.

FIG. 4 depicts a block diagram illustrating a computing apparatus 400consistent with implementations of the current subject matter. Referringto FIGS. 1-3 , at least a portion of the computing apparatus 400 may beused to implement at least a portion of the computing system 110, anapparatus providing the database 120, an apparatus providing theexternal software 130, one or more of the user access devices 140, anaccess device 165, the process 300 and/or the like.

As shown in FIG. 4 , the computing apparatus 400 may include a processor410, a memory 420, a storage device 430, and input/output devices 440.The processor 410, the memory 420, the storage device 430, and theinput/output devices 440 may be interconnected via a system bus 450. Theprocessor 410 may be capable of processing instructions for executionthat may implement operations consistent with those described herein.Such executed instructions may be implement by one or more componentsof, for example, the computing system 110, the user access device 140and/or the access device 165. In some example implementations, theprocessor 410 may be a single-threaded processor. Alternately, theprocessor 410 may be a multi-threaded processor. The processor 410 maybe capable of processing instructions stored in the memory 420 and/or onthe storage device 430 to display graphical information for a userinterface provided via the input/output device 440.

The memory 420 may be a computer readable medium such as volatile ornon-volatile that stores information within the computing apparatus 400.The memory 420 may store data structures representing configurationobject databases, for example. The storage device 430 is capable ofproviding persistent storage for the computing apparatus 400. Thestorage device 430 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device, or other suitable persistentstorage means. The input/output device 440 provides input/outputoperations for the computing apparatus 400. In some exampleimplementations, the input/output device 440 includes a keyboard and/orpointing device. In various implementations, the input/output device 440includes a display unit for displaying graphical user interfaces. Insome aspects, a visual display of one or more table aspects may be basedon table size, table usage/lock history, for read and/or writefunctions, and table load status history. In some aspects, for eachpass/period/run of a decision process described herein, one pixel may bereserved for each individual table. The color value of the pixel may bemade up of the following table properties: 2 bits for actual readlocking; 1 bit for write locking; 1 bit for the load status (loaded,unloaded); and some bits for the table size.

According to some example implementations, the input/output device 440may provide input/output operations for a network device. For example,the input/output device 440 may include Ethernet ports or othernetworking ports to communicate with one or more wired and/or wirelessnetworks (e.g., a local area network (LAN), a wide area network (WAN),the Internet). The input/output device 440 may include one or moreantennas for communication over the network 160 with the computingsystem 110, the user access device 140 and/or the access device 165.Wireless networks may include Wi-Fi, WiMAX, and cellular networks(2G/3G/4G/5G), and/or any other wireless network.

In some example implementations, the computing apparatus 400 may be usedto execute various interactive computer software applications that maybe used for organization, analysis and/or storage of data in variousformats. Alternatively, the computing apparatus 400 may be used toexecute any type of software applications. These applications may beused to perform various functionalities, e.g., planning functionalities(e.g., generating, managing, editing of spreadsheet documents, wordprocessing documents, and/or any other objects, etc.), computingfunctionalities, communications functionalities, etc. The applicationsmay include various add-in functionalities or may be standalonecomputing products and/or functionalities. Upon activation within theapplications, the functionalities may be used to generate the userinterface provided via the input/output device 440. The user interfacemay be generated and presented to a user by the computing apparatus 400(e.g., on a computer screen monitor, etc.).

In some implementations, a machine learning model of a machine learningsystem may evaluate the impact of allocating processes and/orapplications among multiple threads. The model may assume that thefuture use of the allocated memory segments/resource is notsignificantly different from the old one. If so, then the algorithm maymake more accurate allocation decisions for threads to clear physicalmemory. If the usage or performance changes significantly, furthertraining may allow the algorithm to adapt to the changed usage and/orperformance.

The machine learning system may comprise a neural network. The machinelearning system may be trained in an unsupervised or supervised manner.In some implementations, for all considered allocations, the history ofdifferent aspects of memory usage, loading, unloaded and/or the like maybe recorded. This history may include the load status of the memory, theincrease difference of the processing performance, and the memorymapping decisions. The respective values may be retrieved periodicallyby a system process and recorded in the history on a rolling basis. Fromthe load status history of the memory, loads and unloads of each memoryresource may be retrieved. The machine learning system may be trained todistinguish between memory usage for business purposes and memory usagefor housekeeping purposes. If the machine learning system indicates thata memory resource is only used by housekeeping processes it may factorthat parameter in its decision to unload the table. As such memoryresources may be unloaded less than housekeeping processes run and thusover all the system resources may beneficially be dedicated to businesspurpose processes than for housekeeping processes.

The machine learning system may group the loaded memory resources. Thegrouping may serve to limit the machine learning processing/training.The larger the set of memory resources the more complex the algorithm tobe trained and the higher the expected efficiency. On the other hand,the complexity of the algorithm may increase the learningprocessing/training. For each group of memory resources, the machinelearning system may apply an algorithm or model. The described historyof the memory resources of a group may form the input of the algorithm.The output of the algorithm may be an unload decision for each memoryresource and/or memory resource group.

Training the unload decision algorithm may involve using the differenthistorical aspects of the memory resources. A decision to unload amemory resource may be compared with the time until the memory resourceis reloaded again, such as to answer some query request. If that time islong, then that may indicate the decision was right. If the time toreload was short, then it may indicate that the decision was wrong. Ifthe memory resource was not unloaded despite the fact that it was notused afterwards, then the machine learning system may determine that adecision not to unload was likely incorrect. In some aspects, it may beadvantageous to reload memory resource(s) shortly before the firstsubsequent use after a meaningful unload. Reloading may shorten thequery execution time of this first subsequence use by reducing theamount of data in the memory resources and the load time of the memoryresource. For reloading a memory resource, the output level of thealgorithm may include a load decision in addition to the unloaddecision.

One or more aspects or features of the subject matter described hereinmay be realized in digital electronic circuitry, integrated circuitry,specially designed ASICs, field programmable gate arrays (FPGAs)computer hardware, firmware, software, and/or combinations thereof.These various aspects or features may include implementation in one ormore computer programs that are executable and/or interpretable on aprogrammable system including at least one programmable processor, whichmay be special or general purpose, coupled to receive data andinstructions from, and to transmit data and instructions to, a storagesystem, at least one input device, and at least one output device. Theprogrammable system or computing system may include clients and servers.A client and server are generally remote from each other and typicallyinteract through a communication network. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

These computer programs, which may also be referred to as programs,software, software applications, applications, components, or code,include machine instructions for a programmable processor, and may beimplemented in a high-level procedural and/or object-orientedprogramming language, and/or in assembly/machine language. As usedherein, the term “machine-readable medium” refers to any computerprogram product, apparatus and/or device, such as for example magneticdiscs, optical disks, memory, and Programmable Logic Devices (PLDs),used to provide machine instructions and/or data to a programmableprocessor, including a machine-readable medium that receives machineinstructions as a machine-readable signal. The term “machine-readablesignal” refers to any signal used to provide machine instructions and/ordata to a programmable processor. The machine-readable medium may storesuch machine instructions non-transitorily, such as for example as woulda non-transient solid-state memory or a magnetic hard drive or anyequivalent storage medium. The machine-readable medium may alternativelyor additionally store such machine instructions in a transient manner,such as for example, as would a processor cache or other random accessmemory associated with one or more physical processor cores.

To provide for interaction with a user, one or more aspects or featuresof the subject matter described herein may be implemented on a computerhaving a display device, such as for example a cathode ray tube (CRT) ora liquid crystal display (LCD) or a light emitting diode (LED) monitorfor displaying information to the user and a keyboard and a pointingdevice, such as for example a mouse or a trackball, by which the usermay provide input to the computer. Other kinds of devices may be used toprovide for interaction with a user as well. For example, feedbackprovided to the user may be any form of sensory feedback, such as forexample visual feedback, auditory feedback, or tactile feedback; andinput from the user may be received in any form, including acoustic,speech, or tactile input. Other possible input devices include touchscreens or other touch-sensitive devices such as single or multi-pointresistive or capacitive track pads, voice recognition hardware andsoftware, optical scanners, optical pointers, digital image capturedevices and associated interpretation software, and the like.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it used, such a phrase is intendedto mean any of the listed elements or features individually or any ofthe recited elements or features in combination with any of the otherrecited elements or features. For example, the phrases “at least one ofA and B;” “one or more of A and B;” and “A and/or B” are each intendedto mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” Use of the term “based on,” above and in theclaims is intended to mean, “based at least in part on,” such that anunrecited feature or element is also permissible.

The subject matter described herein may be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. The implementations set forth in the foregoingdescription do not represent all implementations consistent with thesubject matter described herein. Instead, they are merely some examplesconsistent with aspects related to the described subject matter.Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations may be provided in addition to those set forth herein.For example, the implementations described above may be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. Other implementations may be within the scope of the followingclaims.

1-20. (canceled)
 21. A system, comprising: at least one data processor;and at least one memory storing instructions which, when executed by theat least one data processor, result in operations comprising: inresponse to a shutdown of a process, waking at least one processingthread of a plurality of processing threads allocated to a databasesystem; allocating a list of memory mappings to the plurality ofprocessing threads, the list of memory mappings allocated to the processand assigned to a processing thread of the plurality of processingthreads; and freeing, by the processing thread, physical memory assignedto the processing thread by the memory mappings.
 22. The system of claim21, wherein the list of memory mappings comprise a subset of memorysegments.
 23. The system of claim 22, wherein the subset of memorysegments are assigned to the processing thread.
 24. The system of claim22, wherein the allocating comprises allocating particular memorysegments to each thread of the plurality of processing threads.
 25. Thesystem of claim 22, further comprising: tracking, during a startup ofthe process, code locations of the process; and tracking, during runtimeof the process and in response to the tracking the code locations,memory segments of the at least one memory allocated to the process. 26.The system of claim 21, further comprising: returning, after all of theplurality of processing threads finish freeing the physical memoryassigned to the plurality of processing threads, control for shuttingdown the process to an operating system of the at least one dataprocessor.
 27. The system of claim 21, wherein the freeing is performedconcurrently by each thread of the plurality of processing threads. 28.The system of claim 21, wherein freeing the physical memory comprisesfreeing memory pages from a page table.
 29. The system of claim 21,wherein the allocating is based on a machine learning model.
 30. Thesystem of claim 29, further comprising: updating the machine learningmodel based on a historic allocation of memory mappings to the pluralityof processing threads.
 31. The system of claim 21, wherein the waking isperformed in response to receiving an indication of the shutdown of theprocess.
 32. A method comprising: in response to a shutdown of aprocess, waking at least one processing thread of a plurality ofprocessing threads allocated to a database system; allocating a list ofmemory mappings to the plurality of processing threads, the list ofmemory mappings allocated to the process and assigned to a processingthread of the plurality of processing threads; and freeing, by theprocessing thread, physical memory assigned to the processing thread bythe memory mappings.
 33. The method of claim 32, wherein the list ofmemory mappings comprise a subset of memory segments.
 34. The method ofclaim 33, wherein the subset of memory segments are assigned to theprocessing thread.
 35. The method of claim 33, wherein the allocatingcomprises allocating particular memory segments to each thread of theplurality of processing threads.
 36. The method of claim 33, furthercomprising: tracking, during a startup of the process, code locations;and tracking, during runtime of the process and in response to thetracking the code locations, memory segments of the at least one memoryallocated to the process.
 37. The method of claim 32, furthercomprising: returning, after all of the plurality of processing threadsfinish freeing the physical memory assigned to the plurality ofprocessing threads, control for shutting down the process to anoperating system of the at least one data processor.
 38. The method ofclaim 32, wherein the freeing is performed concurrently by each threadof the plurality of processing threads.
 39. The method of claim 32,wherein freeing the physical memory comprises freeing memory pages froma page table.
 40. A non-transitory computer readable storage mediumincluding at least one memory storing instructions which, when executedby at least one data processor, result in operations comprising: inresponse to a shutdown of a process, waking at least one processingthread of a plurality of processing threads allocated to a databasesystem; allocating a list of memory mappings to the plurality ofprocessing threads, the list of memory mappings allocated to the processand assigned to a processing thread of the plurality of processingthreads; and freeing, by the processing thread, physical memory assignedto the processing thread by the memory mappings.